There are occasions in various arts when it is desired to form a pasty material into a fillet between two surface parts, which may be parts of one surface, for example, regions bordering a crack in a surface, or parts of separate adjacent or meeting surfaces.
By a fillet is meant an elongated filling between surface parts which may be co-planar, parallel and spaced, or inclined at any angle and may meet or have spaced edges. The fillet may be between the edges of the surface parts or overlie a marginal region of one or both of them. The pasty materials used for producing such fillets are most frequently formulated to set into a solid or near-solid condition some time after application. Fillets commonly have a simple decorative function, but sometimes are required to provide a seal between surface parts and occasionally may have a mechanical function such as contributing to the retention of the surface parts in correct relationship.
One example is the provision of a sealing fillet between a wall of a room, such as a kitchen or bathroom, and a working surface or the surround of a sink, wash-basin or bath which abuts the wall, to prevent water from flowing between the sink, etc., and the wall, as well as to conceal and improve the appearance of the junction. Various manufacturers have produced sealing materials for this purpose in the form of pastes contained in collapsible tubes or cartridges from which the materials can be extruded. However, it is widely recognised that it is difficult for the user of such a tube or cartridge, particularly the home handyman or "do-it-yourself" enthusiast, who may be unskilled, to produce a fillet which both seals against the two surfaces and has a neat and attractive appearance.
A common practice when forming such fillets from pasty materials is to move the nozzle of the extrusion apparatus along the junction between the surfaces approximately in the opposite direction to the direction of flow of the pasty material through the nozzle orifice. The extruded material is simply laid in the junction whilst the nozzle is moved backwardly more or less at the same speed as the extruded fillet of pasty material emerges from the nozzle. The shape of the fillet is determined by the shape of the nozzle orifice and by the surfaces adjacent to the junction. However, it is difficult to maintain by hand the necessary relationship between the nozzle and the two surfaces and the uniform speeds of movement of the nozzle and extrusion of pasty material that are required to produce a fillet of constant cross section. Any lateral movement of the nozzle produces transverse ridges in the fillet. Moreover, by merely laying the fillet into the junction in this way, it is difficult to ensure complete contact of the fillet with both surfaces, as is necessary if a seal is the prime object. If the fillet does not adhere securely, it may subsequently be displaced.
An improved fillet, pressed against the surfaces and therefore adhering more securely, can be obtained by moving the nozzle forwardly, in the same direction as the extrusion of the material, whilst it is pressed against both surfaces adjacent to the junction. With a nozzle of the usual circular cross section, such a fillet has a concave outer surface defined in cross section by the outer edge of the nozzle. However, considerable skill is required in controlling the extrusion of the pasty material and moving the extrusion nozzle so as to maintain an adequate quantity of extruded material in advance of the nozzle to form the fillet, but not so much that material flows onto the surfaces outside the meeting points of the nozzle edge and the surfaces. The latter often happens when an unskilled person attempts to perform this operation, producing an unsightly result. Pasty material which has flowed onto the surfaces is difficult to remove later without disturbing the fillet. The invention enables such an improved fillet to be obtained more easily.
Often the pasty material for forming a fillet is applied from a mass of the material by hand or by use of hand held tools. One example is in the grouting of tiles, in which the usual method is to work the pasty grouting material into the gaps between the tiles with a sponge or cloth and then press it down into the gaps with a narrow tool. Grouting material left on the surfaces of the tiles then has to be removed, and this necessarily limits the kinds of materials that can be used for grouting, since any material having a tendency to adhere strongly to the tile surfaces is not readily removed. Consequently the materials commonly used for grouting do little more than fill the gaps between the tiles and do not contribute significantly to the overall strength of the tiled surface. Furthermore, the appearance of a grouted tiled surface depends to a considerable extent upon the skill of the person applying the grouting material, and is often unsatisfactory or even unsightly.
Another example of the application of pasty material by hand to form a fillet is in the glazing of windows. Conventionally, putty is worked by hand into the rebate of the window frame and against the margins of the glass, and is then pressed home and smoothed off at about 45.degree. to the glass surface with a hand-held putty knife. Whilst a skilled glazier can perform this operation in a short time and produce a neat result, less-skilled operators such as "do-it-yourself" enthusiasts find it a slow and difficult task. Furthermore, because of the need to be able to remove any surplus putty from the glass and from parts of the window frame other than the rebate, it is not convenient to use putties which have strong adhesive characteristics. As a result, after a period of service, putty often separates from the glass and/or the window frame rebate, admitting water which promotes the growth of algae, rotting of the frame or, when frost occurs, may crack the glass or force the putty out of the rebate.
This invention concerns apparatus for extruding pasty materials to form fillets, applicable not only in circumstances in which extrusion is the method commonly used, but also in certain circumstances in which it is more usual to apply the pasty material from a mass by hand or hand-held tools.
Because of the restrictions which have been mentioned, and similar restrictions in other circumstances, various pasty materials which have properties which would be advantageous if they could be used to form fillets between surface parts have not hitherto been used except, perhaps, by skilled operators in particular circumstances. For example, the putties used for glazing usually have, as mentioned, little adhesion to glass or to window frame materials, but pasty materials are available which are capable of strong water-resisting adhesion to such surfaces. If a conventionally-glazed window is broken by an intending intruder, fragments of broken glass usually can be removed from the window frame without difficulty because they are not held by the putty. The present invention enables adhesive putties to be used which will hold fragments of glass in position after a window is broken and make intrusion into a building a good deal more difficult than when conventional putties are used.
Gaps between doors or casement windows and their outer frames have been filled to exclude draughts or for fire protection purposes by applying a pasty material to the frame with the door or window open and then closing the door or window and allowing the pasty material to set. By this method is difficult to ensure that gaps between the door or window and the frame, which are often of varying width, are completely filled. Where the gap is narrow, surplus material is squeezed out when the door or window is closed and has to be removed, but where the gap is wide the amount of material applied may be inadequate so that a seal is not achieved. The present invention enables sealing fillets to be produced with a door or window closed, with no wastage of material.